I'm thinking of puting a Fat Man independent I beam front end in my duece. Has anyone had any experience with the setup? Keith
Talk to Brent, the owner of Fatman. He has one in his '34 Ford Sedan and has put a lot of miles on it. I've talked to him about the set up as I was thinking of building my own based on his design. In the end, it was a lot of work for a small gain in ride and cornering. I'll offer an answer to all the why's above. Maybe, just maybe you want something a little different.
It was an idea marketed in the 80s and failed then as well. You dont see folks lining up for Fatmans either.
If you haven't driven a '32 with a "one-piece" I-beam, I suggest you do. When set up properly (and Henry did it just fine with his wishbone) it will provide a surprisingly nice ride.
There are a lot of bad surprises. You get the wheels leaning in or out and toe in problems. The spring has to be 3-4 times as strong due to the leverage that used to be absorbed by the solid axle.
It was done a lot earlyer than that... Allard used the same basic IFS on his cars ( pic ), and a lot of Brit Special builders did as well. The geometry improved a lot when they started to move the suspension pick up points as far away from the wheel as possible ( like the Ford Truck Twin I-Beam, but with a lower roll centre ), But I'm pretty sure the F/M set up has the pivots in the middle. Good thing is that its a Bolt-In kit. So it's easy to take back out...
Here's a great example of an Allard one gone wrong, not sure if he was going uphill, downhill or round a track but it ain't pretty!
That pic of the red Allard showcases exactly the main shortcoming of a short swing arm rigid kingpin IFS, namely the "pogo stick effect". The suspension geometry should produce negative camber as the car leans over onto the RF tire entering a LH corner. BUT, what ends up happening when the pivot point is above the roll center, is that the entire car jacks up over that wheel using the suspension pivot as leverage. This gives you positive camber where you really really want negative camber, and can cause the LF tire to come plum off the ground (as you can see in that pic). If you're going to go with an IFS, do yourself a favor and at least build one that has good geometry. IMO an IFS doesn't need to be ugly, if done right it will look just as good as any I-beam. There's no sense in doing a bastardized IFS to try and pass it off as an I-beam. Either sack up and build a proper and pretty IFS, or go for the easy looks and tradition of the I-beam. It's like Mr Miyagi says, IFS yes, IFS no . . . . but IFS maybe? Squish! Just like grape.
Why not a version of the old Studebaker Planar system for an IFS with transverse spring? Jeepsters or some other Jeep civilian product used a version of this too.
There will be alot of OPINIONS on this one. The place you are looking for is Fatman Fabrication (http://www.fatmanfab.com/catalogpage.php?page=2) There are other options that you can use too. MG used indepedent on some of its early race cars, and there are some early hot rodders who used independent set-ups that you can look to for inspiration. Not to mention a whole bunch of race inspired IFS. But the other guys here are correct about using a strait axle, there is evidence that a well set up strait axle can be as good or better than an independent set up. Mostly though it is about how the car looks. Fenderless cars generaly look better than cars with IFS. I suppose the debate will continue.
I would think this could drop unsprung weight in front by guesstimated 25% or so, improving ride a bit over equivalent constructon of I beam, but it should hurt handling...keeping it controllable would involve limiting range of motion severely so the truly evil geometry would stay within the sidewall distortion limits of radial tires. Longest possible arms and mounting would improve geometry at the cost of adding more unsprung weight back in... You need suspension stops of some sort because there is going to be a very fine line between just poor geometry and upside down in the ditch geometry... the line Allard racers had to tread. A stout anti-roll bar would be one way of limiting travel and could be arranged to provide stops as well...but tight limits on travel and general firming up to keep handling safe will deteriorate the ride benefit you are presumably chasing. I would think either a real beam or a streetrod independent setup would be superior. As an aside, I would love to see a test in which an Allard is fitted with a stock '36 Ford front end to check results...it's very hard to believe there was any benefit to what they did even with drivers capable of staying right under the sudden death point.
i personally would not use anything from fat man for several reasons. that said, the only suspension that looks right under a duece is a ford axle (under any early ford for that matter). just my opinion , mike
Like you said, the worst thing about a Beam is its unsprung weight. And the fact that hitting a bump with one wheel affects the other wheel on that axle. The absolute beauty of it is its simplicity, and the fact that there is no Camber change. As fucked up as that Allard looks going around the corner ( it looks like the Jacking effect is so severe that BOTH wheels are at full Droop, which would mean there is no suspension at all... it went solid...), it has a couple of things going for it, compared to a Hot Rod with a similar system. It would have a Lower Center of Gravity, Good Racing Tires, and a Driver that is ready for its "Quirks".
When I mocked up a split front axle, the camber changes were drastic with only 3" of wheel travel. That's what I quizzed Fatman about. They said that wheel travel needs to be severely limited. I had a number of early Corvairs years ago and experienced the "tuck a rear wheel" problem a few times. That's why I didn't persue the split front axle idea.
A beam axle point to ponder...A chapter of CORSA, Corvair road racer types, were able to secure Colin Chapman, a man with significant background in suspension design and innovation (!!), to lecture at a meeting. After a lengthy talk on suspension types and their pluses and minuses, one of the group asked CC what he would choose if his future suspension work had to be limited to a single general type. His answer: Early Ford. Why?? It perfectly handled the issues of tire placement, and all else could be developed and improved as needed... Note that he was speaking to a group with experience in racing with swing axles...
"It (Allard) would have a Lower Center of Gravity, Good Racing Tires, and a Driver that is ready for its "Quirks"." Which is exactly why I would love to see an Allard tested as is and then with the stock axle its design was based on...I'm betting its famous modification of its Ford chassis was a liability even in those races in which it remained on the road.
That would be interesting... The closest I can remember to that was a Lister ( Jag or Chev ) that was converted to Kurtis Suspension. So it went from a pretty crude Double A Arm IFS to a Beam with Torsion Bar Springs. Which made it corner better than the other Listers...
Here are some pics of a Lotus Formula Car that Chapman used to try out a version of a Non- Independent Suspension. ( De Dion Rear, and the front cage connects both Wheels, so geometry wise it acts as a Beam) That proves that he had not given up on that Idea, even when the Racers had gotten pretty sophisticated. Ferrari experimented with a DeDion Rear on their F1 Cars as late as '78...
Wow...I think that is a fabricated cage I-beam like Chapman's...except that it is made out of boiler plate and Ford ends instead of that foreign tubing stuff.
Check Flaming River. They offer something like Fatmans but the axle halfs have a pivot point past the center and they use a coilover suspension unit.
Ford truck twin I-beam front ends, get them aligned with the truck loaded or empty, whichever way it's used the most. Like some of the other guys said, change in camber with change in front suspension altitude. Otherwise, tire wear on the outside or inside edge. Would a front end like that ride enough better to justify complicating everything else on the front of the car?
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